121 AUSTRALIAN FIELD ORNITHOLOGY 2004, 21, J2 l- 124 Satin Bowerbird Ptilonorhynchus violaceus and Grey Currawong Strepera versicolor Eating Feijoa Acca sellowiana Petals LAWRENCE E. CONOLE Ecology Australia Pty Ltd, 88b Station Street, Fairfield, Victoria 3078 (Email: [email protected]) Summary This paper reports on the eating of flower petals of the introduced Feijoa (Pineapple Guava) Acca sellowiana by the Satin Bowerbird Ptilonorhynchus violaceus and Grey Currawong Strepera versicolor, in the Otway Ranges, south-western Victoria, in December 2003. A brief revi ew of the eating of Feijoa petals by birds, and the role it plays in pollination in the plant's native and introduced range, is also included. Introduction The following observations were made in the township of Wye River (38°38'S, 143°53'E) on the Otway Ranges coastline between Lome and Cape Otway, south­ western Victoria, during the period 7-14 December 2003. Wye River abuts the Great Ocean Road and the Southern Ocean to the south, and is surrounded on three sides by mixed open forest dominated by tree species such as Mountain Grey Gum Eucalyptus cypellocarpa, Manna Gum E. viminalis and Eurabbie E. bicostata. The understorey is typically open and grassy dominated by Common Tussock-grass Poa labillardierei on drier slopes, with a shrub layer of Prickly Moses Acacia verticillata, Sweet Bursaria Bursaria spinosa, daisy-bushes Olearia spp. and Hop Goodenia Goodenia ovata on moist slopes. Most of the house gardens are predominantly composed of mown grasses and exotic plants amongst remnant forest trees. The house where the observations were made in McCrae Road had no formal garden, but on one side had a flowering Feijoa Acca (Feijoa) sellowiana, 2.5 m high, next to a lounge-room window. Soon after arriving, I noted a 'blue' male Satin Bowerbird Ptilonorhynchus violaceus feeding in the Feijoa, but not until 9 December did I look closely at the nature of the food being sought. The Feijoa is native to southern Brazil, northern Argentina, western Paraguay and Uruguay in South America (Morton 1987), and is a member of the family Myrtaceae. It is also known by horticultural names, most commonly as Pineapple Guava. Feijoa flowers are about 40 mm across, and are characterised by large tufts of long crimson stamens and four large, cupped, fleshy petals, whitish on the outside and purplish within (Popenoe 1920). In Brazil birds are considered to be the principal pollinators (Popenoe 1920, Ryerson1933, Ducroquet & Hickel1997), though bees (Hymenoptera) may pollinate some varieties. The means of pollination by birds is that frugivorous species (see Table 1) attending the flowers to eat the petals receive pollen on their heads and subsequently transfer it to other flowers (Ducroquet & Hickel 1997). In Santa Catarina in Brazil, petals of every Feijoa flower under observation were eaten by the fauna before natural dropping at senescence (Ducroquet & Hickel 1997). AUSTRALIAN 122 CONOLE FIELD ORNITHOLOGY Table 1 A review of birds known or suspected to eat flower petals ofthe Feijoa- known or potential pollinators. Taxonomy and nomenclature of non-Australian taxa follow Monroe & Sibley (1993). * denotes introduced species where observation was made. Species Family/Tribe Count1y Reference Confirmed Pied Currawong Corvidae: Australia Perkins (2002) Strepera graculina Artamini Grey Currawong Corvidae: Australia LEC pers. obs., Strepera versicolor Artamini J. Hill pers. comm. (this paper) Diademed Tanager Fringillidae: Brazil Ducroquet & Hickel (1997) Stephanophorus diadematus Thraupinae Tanager spp. Fringillidae: Brazil Ducroquet & Hickel (1997) Tangara spp. Thraupinae Blue-and-yellow Tanager Fringillidae: Brazil Ducroquet & Hickel (1997) Thraupis bonariensis Thraupinae Azure-shouldered Tanager Fringillidae: Brazil G. Thorp pers. comm. Thraupis cyanoptera Thraupinae (this paper) Sayaca Tanager Fringillidae: Brazil Ducroquet & Hickel (1997) Thraupis sayaca Thraupinae Red Wattlebird Meli phagidae Australia Higgins (2001 ), Anthochaera carunculata Perkins (2002) Spiny-cheeked Honeyeater Meliphagidae Australia D. Holly pers. comm. Acanthagenys rufogularis (this paper) Singing Honeyeater Meliphagidae Australia D. Holly pers. comm. Lichenostomus virescens (this paper) Creamy-bellied Thrush Muscicapidae: Brazil G. Thorp pers. comm. 'litrdus amaurochalinus Turdinae (this paper) *Common Blackbird Muscicapidae: *Australia J. Hill pers. comm. Turdus memla Turdinae (this paper) *New G. Thorp pers. comm. Zealand (this paper) Rufous-bellied Thrush M uscicapidae: Brazil Ducroquet & Hickel (1997) Turdus rufiventris Turdinae Satin Bowerbird Ptilonorhynchidae Australi a LEC pers. obs. (this paper) Ptilonorhynchus violaceus Chalk-browed Mockingbird Sturnidae: Brazil Ducroquet & Hickel (1997) Mimus saturninus Mimini *Common Myna Sturnidae: *New G. Thorp pers. comm. Acridotheres tristis Sturnini Zealand (this paper) Olivaceous Elaenia Tyrannidae: Brazil Ducroquet & Hickel (1997) Elaenia mesoleuca Tyranninae Silvereye Zosteropidae Australia Lawrence (1961) Zosterops latera/is Suspected Rainbow Lorikeet Psittacidae Australia J. McLennan pers. comm. 1hchoglossus haematodus (this paper) Yellow Rosella Psittacidae Australia D. Holly pers. comm. Platycercus elegans flaveolus (this paper) Regent Bowerbird Ptilonorhynchidae Australia J. McLennan pers. comm. Sericulus ch1ysocephalus (this paper) VOL. 21 (3) Satin Bowerbird and Grey Currawong SEPTEMBER 2004 Eat Feijoa Petals 123 Observations Between 9 and 11 December, I watched a 'blue' male Satin Bowerbird eating petals of Feijoa flowers by going from blossom to blossom, grasping and tugging or twisting off the petals with his beak, often more than one petal from each flower, and swallowing them whole. On 11 December, I watched a Grey Currawong Strepera versicolor tear off (and eat) segments of petal rather than whole petals. A series of Weeping Bottlebrush Callistemon viminalis bushes was situated 10-20 m from the Feijoa, and Red WattlebirdsAnthochaera carunculata (and other species such as Yellow-faced Honeyeaters Lichenostomus ch1ysops and New Holland Honeyeaters Phylidonyris novaehollandiae) were feeding from flowers on these plants. On several occasions Red Wattlebirds from the bottlebrushes mobbed the Bowerbird and Currawong in the Feijoa, but did not stay in the Feijoa afterwards, or feed there. Likewise, some Wattlebirds gleaning exudates (manna) from nearby Manna Gums also mobbed the Bowerbird and Currawong in the Feijoa but did not stay or feed in the Feijoa afterwards. On 11 December I estimated that approximately 75 % of the flowers present (n = c. 100) had some or all petals missing. Discussion Australian bird species recorded as eating Feijoa petals include the Red Wattlebird (Mueller 1991 cited in Higgins et a!. 2001, Perkins 2002), Pied Currawong Strepera graculina (Perkins 2002), Silvereye Zosterops lateralis (Lawrence 1961 ), Spiny-cheeked Honeyeater Acanthagenys rufogularis (Doug Holly pers. comm.), Singing Honeyeater Lichenostomus virescens (Doug Holly pers. comm.) and the Common Blackbird Titrdus merula (John Hill pers. comm.). The Grey Currawong has also been observed eating Feijoa petals elsewhere in Victoria (John Hill pers. comm.). In New Zealand two introduced birds, the Common Blackbird and Common Myna Acridotheres tristis, are the chief pollinators of the Feijoa there (G. Thorp pers. comm.). The Regent Bowerbird Sericulus chrysocephalus, Rainbow Lorikeet Thchoglossus haematodus (John McLennan pers. comm.), and Yellow Rosella Platycercus elegans flaveolus (Doug Holly pers. comm.) have also been observed feeding at Feijoa flowers, and it was suspected but not confirmed in those instances that the petals were being eaten. The method by which Red Wattlebirds picked and ate petals described by Perkins (2002) is almost exactly the same as I observed for Satin Bowerbirds at Wye River, with the exception that Bowerbirds often ate multiple petals, rather than just one, from each flower. Despite the presence of Red Wattlebirds, Pied Currawongs and Silvereyes at Wye River during my visit, none of these species was seen to forage in the Feijoa. By 11 December, I estimated that only about 25 % of the flowers on the Feijoa had any remaining petals, and I could find none on the ground beneath the tree. I concluded from this that birds (and possibly mammals such as Common Brush tail Possums Trichosurus vulpecula and Common Ringtail Possums Pseudocheirus peregrinus, which were present in the area) had removed approximately 75% of the flower petals on this tree, perhaps amounting to more than 100 flowers and therefore in excess of 400 petals, during the spring- early summer flowering period. This is consistent with observations made in the Feijoa's native range in Brazil, where all petals are taken by fauna (Ducroquet & Hickel1997). The bird-mediated AUSTRALIAN 124 CONOL E FIELD ORNITHOLOGY pollination process of the Feijoa is clearly a very effective one in its natural range, and has been duplica ted on other land masses where the Feijoa has been introduced, with unrelated frugivorous/omnivorous native and introduced birds. In Australia, Satin Bowerbirds, Grey Currawongs and other frugivorous bird species eat the petals of the introduced Feijoa, and may thus be important pollinators of the Feijoa here. Acknowledgements I thank Harvey Perkins for supplying a copy of his publication; John McLennan (N.S.W.), Doug Holly (S.A.) and John Hill (Victoria) for their personal observations; Geoff Carr (Ecology Australia) for helpful comments; and